hwmon: (ina238) Add support for current limits

Since the shunt voltage register and the current register now report the
same values, use the shunt voltage limit registers to report and adjust
current limits, using the same LSB as the LSB used for the actual current
register.

Handle current register accuracy differences in separate function to
improve code readability.

Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz> # INA780
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 83 insertions, 22 deletions

diff --git a/drivers/hwmon/ina238.c b/drivers/hwmon/ina238.c
index 9dc94eccb750..97f12efcaef4 100644
--- a/drivers/hwmon/ina238.c
+++ b/drivers/hwmon/ina238.c
@@ -335,40 +335,92 @@ static int ina238_write_in(struct device *dev, u32 attr, int channel, long val)
 	}
 }
 
-static int ina238_read_current(struct device *dev, u32 attr, long *val)
+static int __ina238_read_curr(struct ina238_data *data, long *val)
+{
+	u32 lsb = data->current_lsb;
+	int err, regval;
+
+	if (data->config->has_20bit_voltage_current) {
+		err = ina238_read_field_s20(data->client, INA238_CURRENT, &regval);
+		if (err)
+			return err;
+		lsb /= 16;	/* Adjust accuracy */
+	} else {
+		err = regmap_read(data->regmap, INA238_CURRENT, &regval);
+		if (err)
+			return err;
+		regval = (s16)regval;
+	}
+
+	*val = DIV_S64_ROUND_CLOSEST((s64)regval * lsb, 1000);
+	return 0;
+}
+
+static int ina238_read_curr(struct device *dev, u32 attr, long *val)
 {
 	struct ina238_data *data = dev_get_drvdata(dev);
+	int reg, mask = 0;
 	int regval;
 	int err;
 
-	switch (attr) {
-	case hwmon_curr_input:
-		if (data->config->has_20bit_voltage_current) {
-			err = ina238_read_field_s20(data->client, INA238_CURRENT, &regval);
-			if (err)
-				return err;
-		} else {
-			err = regmap_read(data->regmap, INA238_CURRENT, &regval);
-			if (err < 0)
-				return err;
-			/* sign-extend */
-			regval = (s16)regval;
-		}
+	if (attr == hwmon_curr_input)
+		return __ina238_read_curr(data, val);
 
-		/* Signed register. Result in mA */
-		*val = DIV_S64_ROUND_CLOSEST((s64)regval * data->current_lsb, 1000);
-
-		/* Account for 4 bit offset */
-		if (data->config->has_20bit_voltage_current)
-			*val /= 16;
+	switch (attr) {
+	case hwmon_curr_min:
+		reg = INA238_SHUNT_UNDER_VOLTAGE;
+		break;
+	case hwmon_curr_min_alarm:
+		reg = INA238_DIAG_ALERT;
+		mask = INA238_DIAG_ALERT_SHNTUL;
+		break;
+	case hwmon_curr_max:
+		reg = INA238_SHUNT_OVER_VOLTAGE;
+		break;
+	case hwmon_curr_max_alarm:
+		reg = INA238_DIAG_ALERT;
+		mask = INA238_DIAG_ALERT_SHNTOL;
 		break;
 	default:
 		return -EOPNOTSUPP;
 	}
 
+	err = regmap_read(data->regmap, reg, &regval);
+	if (err < 0)
+		return err;
+
+	if (mask)
+		*val = !!(regval & mask);
+	else
+		*val = DIV_S64_ROUND_CLOSEST((s64)(s16)regval * data->current_lsb, 1000);
+
 	return 0;
 }
 
+static int ina238_write_curr(struct device *dev, u32 attr, long val)
+{
+	struct ina238_data *data = dev_get_drvdata(dev);
+	int regval;
+
+	/* Set baseline range to avoid over/underflows */
+	val = clamp_val(val, -1000000, 1000000);
+	/* Scale */
+	val = DIV_ROUND_CLOSEST(val * 1000, data->current_lsb);
+	/* Clamp to register size */
+	regval = clamp_val(val, S16_MIN, S16_MAX) & 0xffff;
+
+	switch (attr) {
+	case hwmon_curr_min:
+		return regmap_write(data->regmap, INA238_SHUNT_UNDER_VOLTAGE,
+				    regval);
+	case hwmon_curr_max:
+		return regmap_write(data->regmap, INA238_SHUNT_OVER_VOLTAGE,
+				    regval);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
 static int ina238_read_power(struct device *dev, u32 attr, long *val)
 {
 	struct ina238_data *data = dev_get_drvdata(dev);
@@ -521,7 +573,7 @@ static int ina238_read(struct device *dev, enum hwmon_sensor_types type,
 	case hwmon_in:
 		return ina238_read_in(dev, attr, channel, val);
 	case hwmon_curr:
-		return ina238_read_current(dev, attr, val);
+		return ina238_read_curr(dev, attr, val);
 	case hwmon_power:
 		return ina238_read_power(dev, attr, val);
 	case hwmon_temp:
@@ -544,6 +596,9 @@ static int ina238_write(struct device *dev, enum hwmon_sensor_types type,
 	case hwmon_in:
 		err = ina238_write_in(dev, attr, channel, val);
 		break;
+	case hwmon_curr:
+		err = ina238_write_curr(dev, attr, val);
+		break;
 	case hwmon_power:
 		err = ina238_write_power_max(dev, val);
 		break;
@@ -582,7 +637,12 @@ static umode_t ina238_is_visible(const void *drvdata,
 	case hwmon_curr:
 		switch (attr) {
 		case hwmon_curr_input:
+		case hwmon_curr_max_alarm:
+		case hwmon_curr_min_alarm:
 			return 0444;
+		case hwmon_curr_max:
+		case hwmon_curr_min:
+			return 0644;
 		default:
 			return 0;
 		}
@@ -627,7 +687,8 @@ static const struct hwmon_channel_info * const ina238_info[] = {
 			   INA238_HWMON_IN_CONFIG),
 	HWMON_CHANNEL_INFO(curr,
 			   /* 0: current through shunt */
-			   HWMON_C_INPUT),
+			   HWMON_C_INPUT | HWMON_C_MIN | HWMON_C_MIN_ALARM |
+			   HWMON_C_MAX | HWMON_C_MAX_ALARM),
 	HWMON_CHANNEL_INFO(power,
 			   /* 0: power */
 			   HWMON_P_INPUT | HWMON_P_MAX |